C# – iTextSharp – Crop PDF File (C#)

I want to crop PDF File using iTextSharp and rectangle (0,1000,600,155). Everything is fine and when you open created *.pdf file you can see only that cropped content, BUT! If you parse that pdf, there are still information and text from not visible part of document, I can't accept that. How can I remove that data completly?

Here is my code sample:

        static void cropiTxtSharp(){
        string file ="C:\\testpdf.pdf";
        string oldchar = "testpdf.pdf";
        string repChar = "test.pdf";
        PdfReader reader = new PdfReader(file);
        PdfDictionary pageDict;
        PdfRectangle rect = new PdfRectangle(0, 1000, 600, 115);
        pageDict = reader.GetPageN(1);
        pageDict.Put(PdfName.CROPBOX, rect);
        PdfStamper stamper = new PdfStamper(reader, new FileStream(file.Replace(oldchar, repChar), FileMode.Create, FileAccess.Write));
        stamper.Close();
        reader.Close();
    }

EDIT:
Here is code which works, I spend some hours but finally I did it 😛

First, add following to project:

using iTextSharp.text.pdf;
using iTextSharp.text;
using iTextSharp.xtra.iTextSharp.text.pdf.pdfcleanup;

Then you can use my code:

    static void textsharpie()
    {
        string file = "C:\\testpdf.pdf";
        string oldchar = "testpdf.pdf";
        string repChar = "test.pdf";
        PdfReader reader = new PdfReader(file);
        PdfStamper stamper = new PdfStamper(reader, new FileStream(file.Replace(oldchar, repChar), FileMode.Create, FileAccess.Write));
        List<PdfCleanUpLocation> cleanUpLocations = new List<PdfCleanUpLocation>();
        cleanUpLocations.Add(new PdfCleanUpLocation(1, new iTextSharp.text.Rectangle(0f, 0f, 600f, 115f), iTextSharp.text.BaseColor.WHITE));
        PdfCleanUpProcessor cleaner = new PdfCleanUpProcessor(cleanUpLocations, stamper);
        cleaner.CleanUp();
        stamper.Close();
        reader.Close();
    }

Unfortunatelly I can't use that code if I want to commercialize my application without paying for license, so I had to think on different library…